Shuttle lock

ABSTRACT

A shuttle lock for maintaining a patient&#39;s residual limb in a prosthetic limb socket includes: (a) a housing having a distal surface adapted to abut an inside surface of a prosthetic limb socket, a substantially concave proximal surface and a hole extending into the center of the proximal surface, where the hole is adapted to receive a plunger pin carried on a patient&#39;s residual limb; (b) a lock positioned within the housing for securing the plunger pin received in the hole; and (c) means for securing the housing of the shuttle lock within the prosthetic limb socket; (d) where the concave proximal surface includes at least one radial groove which is adapted to guide the plunger pin into the hole. Preferably the housing is substantially cylindrical in the concave proximal surface includes a plurality of the radial grooves circumferentially distributed thereabout, where the radial grooves extend substantially from and outer circumference of the concave proximal surface to an outer circumference of the hole. A covering adapted to be worn on a patient&#39;s residual limb is also provided, where the covering includes the plunger pin extending from a distal end of the covering, and also includes a projection extending distally therefrom that is adapted to be received within the radial groove on the proximal surface of the shuttle lock so as to reduce rotation of the patient&#39;s residual limb and covering with respect to the prosthetic limb socket when the plunger pin is secured within the hole of the shuttle lock. Preferably, the covering includes a plurality of ribs extending distally therefrom and oriented radially with respect to the plunger pin, so that the ribs are adapted to be received within the radial grooves to provide the anti-rotation.

BACKGROUND

[0001] The present invention relates to prosthetic devices, and moreparticularly, to a shuttle lock for securing a patient's residual limbin a prosthetic limb socket.

[0002] Conventional shuttle locks for securing a patient's residual limbin a prosthetic limb socket are typically disc-shaped and mounted withina distal end of the prosthetic limb socket. The shuffle locks typicallyinclude an axial hole extending therethrough and include aspring-loaded, reciprocating pawl cooperating with the axial hole toengage the sloping teeth of a ratcheted plunger pin extending from adistal end of a covering carried on the patient's residual limb.Accordingly, when the patient wishes to don the prosthetic limb, thepatient will first don the covering onto his or her residual limb suchthat the plunger pin extends distally therefrom and will then insert theresidual limb into the prosthetic limb socket such that the plunger pinis received within the axial hole of the shuttle lock and is securedtherein by the spring-loaded pawl. Such shuttle locks will also includea release mechanism that removes the pawl from the axial hole of theshuttle lock so that the patient can disengage the plunger pin from theshuffle lock and thus remove his or her residual limb from theprosthetic limb socket.

[0003] Although most shuttle locks include a substantially concaveproximal surface, where the axial hole centers at the bottom of theconcavity, to facilitate locating the plunger pin into the center holeof the shuffle lock, it is sometimes a problem for the patients tolocate the center hole of the shuttle lock while inserting his or herresidual limb into the prosthetic limb socket. Another known problem isthat for residual limbs having a more conical or cylindrical shape, thepatient may experience undesirable rotation of the prosthetic limbsocket with respect to his or her residual limb.

[0004] Yet another known disadvantage with conventional shuttle locks isthat the design of the shuttle lock allows the plunger pin to “wiggle”within the axial hole, which leads to wear in the shuttle lock andprosthetic limb socket components. Since the shuttle lock is desirablylow in profile (axial thickness) and since, in some cases, substantialradial clearance is provided between the outer diameter of the plungerpin and the inner diameter of the axial hole (to compensate formis-aligned engagement), excess ‘play’ results in the plunger pin.

[0005] The proximal surface of the prosthetic limb socket and the distalsurface of the shuttle lock abutting the proximal surface at the distalend of the prosthetic limb socket are typically designed to be perfectlyflat such that when the shuttle lock is bolted into the distal end ofthe prosthetic limb socket, “binding” will not be experienced betweenthe two abutting surfaces. However, if these two abutting surfaces arenot totally flat and/or totally parallel, binding of the plastic shuttlelock may occur, which could lead to damage of the shuttle lock and/orthe prosthetic limb socket.

[0006] Accordingly, a need exists for an improved shuttle lock whichassists a patient in locating the axial hole of the shuttle lock withthe plunger pin extending from his or her residual limb; a shuttle lockin which the plunger pin is stabilized within the axial hole whensecured therein so as to reduce wear on the shuttle lock and/orprosthetic limb socket components; a shuttle lock which reduces thechances of binding between the abutting surfaces of the shuttle lock andprosthetic limb socket; and a shuttle lock that is easier to fabricateand maintain.

SUMMARY

[0007] One aspect of the present invention provides a shuttle lock formaintaining a patient's residual limb in a prosthetic limb socket, wherethe shuttle lock includes (a) a housing having a distal surface adaptedto abut an inside surface of a prosthetic limb socket, a substantiallyconcave proximal surface and a hole extending into the center of theproximal surface, where the hole is adapted to receive a plunger pincarried on a patient's residual limb; (b) a lock positioned within thehousing for securing the plunger pin received in the axial hole; and (c)means for securing the housing of the shuttle lock within the prostheticlimb socket; (d) where the concave proximal surface includes at leastone radial groove which is adapted to guide the plunger pin into theaxial hole. Preferably the housing is substantially cylindrical in theconcave proximal surface includes a plurality of the radial groovescircumferentially distributed thereabout, where the radial groovesextend substantially from and outer circumference of the concaveproximal surface to an outer circumference of the axial hole. It ispreferred that the lock involves a spring-loaded pawl positioned withinthe housing for engagement with a ratcheted plunger pin; however it iswithin the scope of the present invention to provide other forms oflocks suitable for securing the plunger pin within the axial holeextending into the shuttle-lock housing, such as a magnetic lock, forexample.

[0008] Another aspect of the present invention provides a shuttle lockfor maintaining a patient's residual limb in a prosthetic limb socketthat includes: (a) a housing having a distal surface adapted to abut aninside surface of a prosthetic limb socket, a hole extending axiallytherethrough and adapted to receive a plunger pin carried on a patient'sresidual limb; (b) a lock positioned within the housing for securing theplunger pin received in the axial hole; (c) means for securing thehousing within a prosthetic limb socket; and (d) an annular protrusionextending distally from the distal opening of the axial hole, where theannular protrusion is coaxial with the axial hole and has an innerdiameter substantially equal to the diameter of the axial hole so thatthe annular protrusion assists in stabilizing the plunger pin whenreceived within the axial hole. Preferably, the protrusion extendsthrough a hole in the prosthetic limb socket and has a heightsubstantially equal to the thickness of the prosthetic limb socketmaterial. Furthermore, it is preferred that the axial hole extendingthrough the shuttle lock is provided by a hardened or metal bushingextending axially through the housing and distally from the housing toprovide the annular protrusion. This bushing provides reinforcement tothe shuttle lock and substantially reduces the amount of wear impartedby the plunger pin onto the shuttle lock components due to its hardnessand wear characteristics.

[0009] Another aspect of the present invention provides a shuttle lockfor maintaining the patient's residual limb in a prosthetic limb socketthat includes: (a) a housing having a distal surface, a substantiallyconcave proximal surface and a hole extending into the center of theproximal surface which is adapted to receive a plunger pin carried on apatient's residual limb; (b) a lock positioned within the housing forsecuring the plunger pin received in the axial hole; (c) a plurality ofholes or bores extending into the distal surface of the housing forreceiving a corresponding plurality of bolts or screws which are used tosecure the housing within the prosthetic limb socket; and (d) at leastone projection extending from the distal surface of the housing, wherethe projection is adapted to abut an inside surface of the prostheticlimb socket and assume the majority of the load distribution when theshuttle lock is secured in the prosthetic limb socket. By reducing theload distribution on the distal surface of the housing, the projectionthereby substantially reduces “binding” between the distal surface ofthe housing and the inside surface of the prosthetic limb socket.Preferably, the distal surface of the housing is substantially flat andthe projection has a substantially flat distal surface on a planeparallel to the distal surface of the housing. It is also preferred thatthere are a plurality of projections, where each projection issubstantially annular and surrounds a respective one of the bores, andthat the projections extend distally for a distance equal toapproximately 0.001 to 0.020 inches.

[0010] Another aspect of the present invention provides a shuttle lockfor maintaining a patent's residual limb in a prosthetic limb socketthat includes: (a) an upper housing plate having a substantially concaveproximal surface, a distal end and an axial hole extending completelytherethrough, into the center of the substantially concave proximalsurface and out through the distal end; (b) a lower housing plate havinga proximal end removably coupled to the distal end of the upper housingplate, a distal surface adapted to abut an inside surface of aprosthetic limb socket and an axial hole extending into the proximalend, coaxial with the axial hole extending through the upper housingplate and adapted to receive a ratcheted plunger pin carried on apatient's residual limb; (c) a spring-loaded pawl, mounted within thelower housing plate for reciprocation radially into and out from theaxial hole extending into the lower housing plate, and adapted to engagethe plunger pin received in the axial hole; and (d) means for securingthe lower housing plate within the prosthetic limb socket. Preferably,the distal end of the upper housing plate and the proximal end of thelower housing plate are substantially flat.

[0011] It is also preferred that the shuttle lock includes: (e) a pushrod slidably received within the lower housing plate; (f) a lever,mounted to the lower housing plate, operatively coupled between the pushrod and the pawl such that movement of the push rod to a first positioncauses the pawl to reciprocate at least partially into the axial holeand movement of the push rod to a second position causes the pawl toreciprocate out from the axial hole; and (g) a spring biasing the pushrod to the first position. Preferably, the pawl is slidingly positionedin a first radial hole extending into an outer circumferential surfaceof the lower housing plate and out through the axial hole extending intothe lower housing plate, the push rod is slidably positioned in a secondradial hole extending into the outer circumferential surface of thelower housing plate, the lever is pivotably mounted to the flat proximalsurface of the lower housing plate; and the shuttle lock furthercomprises a first pin extending from the first end of the lever, throughan opening in the flat proximal surface of the lower housing plate andinto the push rod, and a second pin extending from a second end of thelever, through an opening in the flat proximal surface of the lowerhousing plate and into the pawl. This second pin extending through aproximal surface of the lever is preferably slidingly removable from thelever and pawl so as to facilitate simple replacement of the pawl in thelower housing plate. Because the pawl is slidingly received in the firstradial hole, once the second pin is removed, the pawl can be slid outfrom the lower housing plate and replaced if damaged or worn.

[0012] Another aspect of the present invention provides a prostheticlimb that includes: (a) a covering adapted to be worn on a patient'sresidual limb, where the covering includes a plunger pin extending froma distal end of the covering; (b) a prosthetic limb socket adapted toreceive the patient's residual limb with the covering worn thereon; and(c) a shuttle lock mounted within the prosthetic limb socket, at adistal end of the prosthetic limb socket, where the shuttle lockincludes a substantially concave proximal surface, a hole extending intothe center of the proximal surface for receiving the plunger pin, and alock for securing the plunger pin within the axial hole. The proximalsurface of the shuttle lock includes at least one radial groove and thecovering preferably includes a projection extending distally therefromwhich is adapted to be received within the radial groove on the proximalsurface of the shuttle lock so as to reduce rotation of the patient'sresidual limb and covering with respect to the prosthetic limb socketwhen the plunger pin is secured within the axial hole of the shuttlelock. Preferably, the concave proximal surface of the shuttle lockincludes a plurality of radial grooves circumferentially distributedthereabout and the covering includes a plurality of ribs extendingdistally therefrom and oriented radially with respect to the plungerpin, so that the ribs are adapted to be received within the radialgrooves to provide the anti-rotation discussed above.

[0013] Accordingly, it is an object of the present invention to providea shuttle lock adapted to assist a patient in donning a prosthetic limbsocket, and specifically, a shuttle lock that assists the patient inlocating the axial hole extending through the shuttle lock with theplunger pin extending distally from the covering worn on the patient'sresidual limb. It is a further object of the present invention toprovide a shuttle lock that is less susceptible to wear, and a shuttlelock that is designed to reduce binding between the shuttle lock housingand the prosthetic limb socket. It is a further object of the presentinvention to provide a prosthetic limb that is designed to reduceundesirable rotation between the patient's residual limb with respect tothe prosthetic limb socket. Finally, it is an object of the presentinvention to provide a shuttle lock that is relatively uncomplicated andinexpensive to manufacture; and that is relatively easy to maintain.These and other objects and advantages of the present invention will beapparent from the following description, the attached drawings and theappended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014]FIG. 1 is an exploded, perspective view of a prosthetic limbincluding the shuttle lock and residual limb covering of the preferredembodiment of the present invention;

[0015]FIG. 2 is an exploded, perspective view of the preferredembodiment of the shuttle lock;

[0016]FIG. 3 is a perspective view of the preferred embodiment of theshuttle lock;

[0017]FIG. 4 is a cross-sectional view of the preferred embodiment ofthe shuttle lock mounted within a prosthetic limb socket;

[0018]FIG. 5 is a magnified view of the area indicated as “5” in FIG. 4;

[0019]FIG. 6 is a cross-sectional view of the pawl for use with thepreferred embodiment of the shuttle lock;

[0020]FIG. 7A is a top plan view of the lower housing plate of thepreferred embodiment of the shuttle lock showing the lock components ina “locking” position;

[0021]FIG. 7B is a top plan view of the preferred embodiment of theshuttle lock showing the lock components in a “locking” position;

[0022]FIG. 8A is a top plan view of the lower housing plate of thepreferred embodiment of the shuttle lock showing the lock components ina “unlocked” position; and

[0023]FIG. 8B is a top plan view of the preferred embodiment of theshuttle lock showing the lock components in the “unlocked” orientation.

DETAILED DESCRIPTION

[0024] As shown in FIG. 1, a socket assembly 10 of a prosthetic limb inaccordance with the present invention will include a hard plastic outersocket 12, and, preferably, a covering that includes a soft andresilient suspension sleeve 14 rolled onto the patient's residual limb,surrounded by a knitted sock 15. The suspension sleeve is formed tosnugly fit over the residual limb of the patient and to provide comfortto the residual limb of the patient when the prosthetic limb is worn bythe patient. The suspension sleeve 14 has a plunger pin 16 extendingdistally from a distal end of the suspension sleeve, and the sock 15includes a hole 17 that allows the plunger pin 16 to extendtherethrough. The plunger pin 16 is adapted to engage with and lockwithin a shuttle lock 18 releasably mounted within an extended portion20 of the outer socket 12. The preferred embodiment of the shuttle lock18 includes an axial channel or hole 22 extending axially therethroughfor receiving and securing the plunger pin 16 therein. A spring loadedpawl 24 (see FIGS. 2, 4, 7A, 7B, 8A and 8B) extending within the axialhole 22 engages with teeth 26 of the ratcheted plunger pin 16 such thatthe pawl 24 and the shape of the teeth 26 allow the locking pin to beeasily inserted within the axial hole, yet prohibit the locking pin frombeing extracted again from the axial hole 22. A spring loaded push rod28 may be pressed by the patient to disengage the pawl 24 extendingwithin the axial hole 22 from the teeth 26, thereby allowing the plungerpin 16 to be extracted again from the axial hole. The spring loadedrelease and locking mechanisms will be described in greater detailbelow.

[0025] The outer socket 12 is typically created by heating athermoplastic “preform” cone until it is sufficiently soft and flexible,stretching the heated cone over a positive cast of the amputee'sresidual limb, and then vacuum forming the cone in place over thepositive cast. Alternatively, the outer socket can be fabricated byheating an extruded sheet of thermoplastic material and wrapping thesheet over the positive cast; or by a laminating process using a fiberreinforced, thermoset plastic. The distal end of the positive castpreferably includes an extended portion or a blank attached thereto toprovide for the dimensions of the shuttle lock 18. Therefore, when theheated cone is stretched over this modified positive cast, the extendedportion 20 of the outer socket will be created. The suspension sleeve 14is typically formed from a pliable, silicone material and includes theplunger pin 16 and associated support flange (not shown) molded therein.An example of a suspension sleeve suitable for use with the presentinvention includes an “Alpha” locking liner, commercially available fromOhio Willowood Co.

[0026] The distal end 30 of the shuttle lock 18 has four threaded holes32 which are aligned with four holes extending through the distal end 34of the outer socket 12. A conventional pyramid plate 36 includes fourholes 38 which are to be aligned with the four threaded holes 32 of theshuttle lock 18. Accordingly, four threaded screws or bolts 40 are usedto attach the pyramid plate 36 to the distal end 34 of the outer socketand simultaneously secure the shuttle lock 18 within the extendedportion 20 of the outer socket. As is known to those of ordinary skill,a pyramidal boss 42 formed integrally with the pyramid plate 36 isprovided to attach an upright assembly (not shown) of the prostheticlimb to the distal end of the prosthetic limb socket assembly 10.

[0027] As shown in FIGS. 2, 3 and 4, the preferred embodiment of theshuttle lock 18 includes a disc shaped, upper housing plate 44 and adisc shaped, lower housing plate 46, removably connected together by aplurality of screws 48 extending upward through holes 50 in the lowerhousing plate and threaded into holes (not shown) in the flat distalsurface 52 of the upper housing plate 44. The upper housing plate 44 hasa substantially concave proximal surface 54 and includes a plurality ofgrooves 56 extending radially, substantially from an outer circumferenceof the plate 44 to an outer circumference of the central hole 58 in theupper housing plate 44. The central hole 58 opens to the axial hole 22when the upper and lower housing plates are connected together. Theradial grooves 56 are evenly distributed circumferentially thereaboutand act to assist the patient in guiding the plunger pin 26 from thesubstantially concave proximal surface 54 to the axial hole 22. Forexample, when the patient inserts the plunger pin 26 carried on his orher residual limb into the socket 12, it is sometimes difficult tolocate the center hole 22 and the plunger pin 26 will first contact theconcave proximal surface 54, and slide around thereon. When the plungerpin slides into one of the grooves 56, the shape of the grooves willlikely prevent the plunger pin from sliding out again and distalpressure on the plunger pin will cause it to slide radially within thegroove 56 towards the axial hole 22 until it is received therein. Aswill be discussed in further detail below, the radial grooves 56 mayalso cooperate with ribs extending from the suspension sleeve tosubstantially limit rotation of the patient's prosthetic limb withrespect to the outer socket 12.

[0028] The upper and lower housing plates 44, 46 are preferably moldedfrom a rigid plastic material such as DELRIN. However, it is within thescope of the present invention that the upper and lower housing plates44, 46 may also be made from other suitable, rigid materials such asnylon, aluminum, steel, etc.

[0029] As shown primarily in FIGS. 1, 4 and 5, the distal surface 58 ofthe lower housing plate 46 is substantially flat and designed to lie ona plane parallel to the flat proximal inner surface 60 at the distal end34 of the outer socket 12. The parallel orientation of the two surfaces58, 60 substantially prevents binding (or twisting) of the shuttle lock18 with respect to the socket 12 when the bolts 40 are tightened.However, because it is very difficult to ensure that both surfaces 58,60 are perfectly parallel, a plurality of annular projections 62 andprovided on the distal surface 58 of the lower housing plate 46 toreduce surface area contact between the lower housing plate 46 and theproximal inner surface 60 at the distal end of the prosthetic limbsocket. Preferably, four of such annular projections 62 are provided,where each of the annular projections 62 encircle the threaded holes 32extending into the distal surface 58 of the lower housing plate 46. Inthe preferred embodiment, the projections are 0.012 inches high, but itis within the scope of the invention to provide 0.0001 to 0.020 inchhigh projections. These projections 62 are adapted to assume themajority of the clamping force between the housing of the shuttle lock18 and the prosthetic limb socket 12 when the housing is secured withinthe prosthetic limb socket by the bolts 40, thereby substantiallyreducing “binding” between distal outer surface 58 of the housing andthe proximal inner surface 60 of the prosthetic limb socket.

[0030] As shown primarily in FIGS. 1, 2 and 4, the lower housing plate46 also preferably includes a hardened bushing 64 received within a hole66 extending axially through the center of the lower housing plate 46.The bushing 64 is preferably made from Bronze 660, however other metalsor hardened materials are also suitable for the present invention. Theinner diameter of the bushing 64 provides the axial hole 22 forreceiving the plunger pin 26 therein. The hole 66 includes a shoulder 68extending radially inwardly from the proximal surface 70 of the lowerhousing plate 46 that engages an outwardly extending flange 72 of thebushing 64, which maintains the bushing 64 within the hole 66. Thebushing 64 also includes a portion 74 that extends axially therefrom ina distal direction to protrude distally from the distal surface 58 ofthe lower housing plate 46. This protrusion 74 preferably extends adistance equal to the thickness of the outer socket 12 (plus the heightof the projections 62) so that the protrusion 74 does not extenddistally from the distal surface 76 of the outer socket 12. This bushing64 provides a reinforcing surface to the axial hole 22, thus minimizingwear caused by the plunger pin 26 and the protrusion 74 extends theaxial hole distally for the thickness of the outer socket 12 to providea further level of stabilization to the plunger pin when received withinthe axial hole 22, while not adding any profile to the shuttle lock 18.

[0031] In an alternate embodiment, the bushing 64 is not used, and thevolume of the lower housing plate 44 formerly taken by the bushing 64(including the protrusion 74) is taken by the material of the lowerhousing plate, integrally formed together. While such an alternateembodiment does not provide the wear resistance of the metal bushing 64,the protrusion extending from the distal end of the lower housing platestill reduces excessive wear by reducing “wiggle” in the plunger pin.This alternate embodiment is also less expensive to produce.

[0032] As shown primarily in FIGS. 2, 3, 7A and 8A, the pawl 24 ispositioned to reciprocate within a radial channel 76 extending radiallyinto the outer circumferential surface of the lower housing plate 46into the hole 68. A radial hole 78 extends through the side of thebushing 64 to allow the pawl 24 to extend into and out from the axialhole 22 provided by the bushing 64. The push rod 28 is also positionedfor reciprocation in a radial channel 80 extending radially into theouter circumferential surface of the lower housing plate 46. The radialchannels 76, 80 are separated radially from one another at an angle ofapproximately 19°. A lever 82 is seated in a depression 84 formed intothe flat proximal surface 70 of the lower housing plate 46. A first endof the lever is coupled to the pawl 24 by a pin 86 extending axiallythrough the lever 82, through a groove 88 extending axially through theflat proximal surface 70 of the lower housing plate 46, into the radialchannel 76 and into a slot 90 (see FIG. 6) extending into the pawl 24.The lever 82 is pivotly coupled to the push rod by another pin 92, whichextends through one end of the lever, through a second groove 94extending axially through the flat proximal surface 70 of the lowerhousing plate 46, into the radial channel 80 and into a slot 96extending into the push rod 28. A pivot pin 98 pivotally couples thelever 82 to the depression 84 formed into the flat proximal surface 70of the lower housing plate 46. Grooves 88 & 94 allow pins 86 & 92,respectively, to travel radially in the lower housing plate 46 duringpivoting of the lever 82.

[0033] As shown in FIGS. 7A and 7B, a spring 100 is positioned on thepush rod 28 between the outer circumferential surface of the lowerhousing plate 46 and a flange 102 extending from the push rod to biasthe push rod 28 radially outwardly, which causes the lever 82 to pivotcounterclockwise on the pivot pin 98, which in turn causes the pawl 24to be pushed radially inwardly so that at least the tapered edge 104 ofthe pawl extends into the axial hole 22. In this position of the pawl24, the shuttle lock is in a “locking” position.

[0034] As shown in FIGS. 8A and 8B, by applying radial pressure (shownby arrow P) to the radial end 106 of the push rod 28, the lever 82 willbe caused to rotate clockwise, which in turn forces the pawl 24 towithdraw radially from the axial hole 22, thus releasing the plunger pin16 (if present within the axial hole 22).

[0035] Because at least the pin 86 is easily removed from the assembly,the pawl 24 may be easily removed, inspected and/or replaced by removingthe pin 86 and sliding out the pawl 24 from the radial channel 76. A newpawl 24 may be inserted into the radial channel 76 and the pin may bereinserted to secure the pawl 24 back again within the radial channel76.

[0036] As shown in FIG. 1, the knitted sock 15 includes a cap 106 formedonto or bonded to its distal end, where the plunger ping 16 extendsdistally through the center of the cap 106. The cap 106 includes aplurality of projections extending distally therefrom in the form ofradial ribs 108, evenly spaced circumferentially thereabout. The cap 106and ribs 108 are preferably formed from a rubber or rubber-like materialthat acts to grip the hard plastic material of the shuttle lock housing.The ribs 108 are adapted to be received in the radial grooves 56 presentin the concave proximal surface 54 of the shuttle lock housing, therebylimiting the amount of undesirable rotation experienced by the patient'sresidual limb with respect to the prosthetic limb socket 12.

[0037] Referring to FIG. 2, the threaded holes 32 in the distal end ofthe shuttle lock 18 are provided by nuts 110 respectively seated inhexagonal depressions 112 extending into the proximal surface 70 of thelower housing plate 46. Pins 114 are used to help secure the upper 20and lower housing plates 44, 46 together without rotation with respectto each other.

[0038] Having described the invention in detail and by reference topreferred embodiments thereof, it will be apparent that modificationsand variations are possible without departing from the scope of theinvention as defined by the following claims:

What is claimed is:
 1. A shuttle-lock for maintaining a patient'sresidual limb in a prosthetic limb socket, the shuttle-lock comprising:a housing having a distal surface adapted to abut an inside surface of aprosthetic limb socket, a substantially concave proximal surface and ahole extending into the center of the proximal surface, the hole beingadapted to receive a plunger pin carried on a patient's residual limbtherein; a lock positioned within the housing for securing the plungerpin received in the hole; and means for securing the housing within aprosthetic limb socket; the concave proximal surface including at leastone radial groove adapted to guide the plunger pin into the hole.
 2. Theshuttle-lock of claim 1, wherein the housing is substantiallycylindrical and the concave proximal surface includes a plurality ofradial grooves circumferentially distributed thereabout.
 3. Theshuttle-lock of claim 2, wherein the radial grooves extend substantiallyfrom an outer circumference of the concave proximal surface to an outercircumference of the hole.
 4. A shuttle lock for maintaining a patient'sresidual limb in a prosthetic limb socket, the shuttle-lock comprising:a housing having a distal surface adapted to abut an inside surface of aprosthetic limb socket, a proximal surface and a hole extendingcompletely therethrough into a proximal opening in the proximal surfaceand out through a distal opening in the distal surface, the hole havinga diameter and being adapted to receive a plunger pin carried on apatient's residual limb therein; a lock positioned within the housingfor securing the plunger pin received in the hole; and means forsecuring the housing within a prosthetic limb socket; and an annularprotrusion extending distally from the distal opening of the hole, theannular protrusion being coaxial with the hole and having an innerdiameter substantially equal to the diameter of the hole, whereby theannular protrusion assists in stabilizing the plunger pin when receivedwithin the hole.
 5. The shuttle lock of claim 4, wherein the protrusionextends distally for a distance approximately equal to a thickness ofthe prosthetic limb socket.
 6. The shuttle lock of claim 5, furthercomprising a hardened bushing mounted within the housing and providingthe hole, the bushing extending distally from the housing to provide theannular protrusion.
 7. A shuttle-lock for maintaining a patient'sresidual limb in a prosthetic limb socket, the shuttle-lock comprising:a housing having a distal surface, a substantially concave proximalsurface and a hole extending into the center of the proximal surface,the hole being adapted to receive a plunger pin carried on a patient'sresidual limb therein; a lock positioned within the housing for securingthe plunger pin received in the hole; a plurality of bores extendinginto the distal surface of the housing for receiving a correspondingplurality of bolts, the bores and bolts cooperating to secure thehousing within the prosthetic limb socket; and at least one projectionextending from the distal surface of the housing, the projection beingadapted to abut an inside surface of a prosthetic limb socket; wherebythe projection is adapted to assume the majority of the loaddistribution on the distal end of the housing when the housing issecured within the prosthetic limb socket by the bolts.
 8. Theshuttle-lock of claim 7, wherein the distal surface of the housing issubstantially flat and the projection has a substantially flat distalsurface on a plane parallel to the distal surface of the housing.
 9. Theshuttle-lock of claim 8, further comprising a plurality of theprojections.
 10. The shuttle-lock of claim 9, wherein each projection issubstantially annular and surrounds a respective one of the bores. 11.The shuttle-lock of claim 9, wherein the projections extend distally fora distance equal to approximately 0.001 to 0.020 inches.
 12. Ashuttle-lock for maintaining a patient's residual limb in a prostheticlimb socket, the shuttle-lock comprising: an upper housing plate havinga substantially concave proximal surface, a distal end and an axial holeextending completely therethrough, into the center of the substantiallyconcave proximal surface and out through the distal end; a lower housingplate having a proximal end removably coupled to the distal end of theupper housing plate, a distal surface adapted to abut an inside surfaceof a prosthetic limb socket and an axial hole extending into theproximal end, coaxial with the axial hole extending through the upperhousing plate and adapted to receive a ratcheted plunger pin carried ona patient's residual limb; a spring-loaded pawl, mounted within thelower housing plate for reciprocation radially into and out from theaxial hole extending into the lower housing plate, and adapted to engagethe ratcheted plunger pin received in the hole; and means for securingthe lower housing plate within a prosthetic limb socket.
 13. Theshuttle-lock of claim 12, wherein the distal end of the upper housingplate and the proximal end of the lower housing plate are substantiallyflat.
 14. The shuttle-lock of claim 13, further comprising: a push rodslidably received within the lower housing plate; a lever, mounted tothe lower housing plate, operatively coupled between the push rod andthe pawl such that movement of the push rod to a first position causesthe pawl to reciprocate at least partially into the axial hole extendinginto the lower housing plate and movement of the push rod to a secondposition causes the pawl to reciprocate out from the hole extending intothe lower housing plate; and a spring biasing the push rod to the firstposition.
 15. The shuttle-lock of claim 14, wherein: the pawl isslidingly positioned in a first radial hole extending into an outercircumferential surface of the lower housing plate and out through theaxial hole extending into the lower housing plate; the push rod isslidingly positioned in a second radial extending into the outercircumferential surface of the lower housing plate; the lever ispivotally mounted to the flat proximal surface of the lower housingplate, having a first end positioned over the push rod and a second endpositioned over the pawl; and the shuttle-lock further comprises a firstpin extending from the first end of the lever, through an opening in theflat proximal surface of the lower housing and into the push rod, and asecond pin extending from the second end of the lever, through anopening in the flat proximal surface of the lower housing and into thepawl.
 16. The shuttle-lock of claim 15, wherein the second pin extendsthrough a proximal surface of the lever and is slidingly removable fromthe lever and pawl so as to facilitate simple replacement of the pawl inthe lower housing plate.
 17. A prosthetic limb comprising: a coveringadapted to be worn on a patient's residual limb, the covering includinga plunger pin extending from a distal end thereof; a prosthetic limbsocket adapted to receive the patient's residual limb with the coveringworn thereon; and a shuttle-lock mounted within the prosthetic limbsocket, at a distal end of the prosthetic limb socket, the shuttle-lockincluding a substantially concave proximal surface, a hole extendinginto the center of the proximal surface for receiving the plunger pin,and a lock for securing the plunger pin within the hole; the proximalsurface of the shuttle-lock further including at least one radialgroove.
 18. The prosthetic limb of claim 17, wherein the coveringfurther includes a projection extending distally therefrom, and theprojection is adapted to be received within the radial groove on theproximal surface of the shuttle-lock so as to reduce rotation of thepatient's residual limb and covering with respect to the prosthetic limbsocket when the plunger pin is secured within the hole of theshuttle-lock.
 19. The prosthetic limb of claim 18, wherein the concaveproximal surface of the shuttle-lock includes a plurality of radialgrooves circumferentially distributed thereabout and the coveringincludes a plurality of ribs extending distally therefrom and orientedradially with respect to the plunger pin, the ribs being adapted to bereceived within the radial grooves.
 20. The prosthetic limb of claim 18,wherein the projection is formed from a rubberlike material.